1. Field of the Invention
Aspects of the present invention relate to a power supply device, and more particularly, to a power supply device for supplying power to an electronic device, and a power supplying method for the power supply device.
2. Description of the Related Art
In general, a portable electronic device obtains its operating power from an adapter connected to an external power source, from a built-in battery, or from an external power supply device (such as an external battery).
A conventional external power supply device operates in either a charging mode or a discharging mode for bidirectional control. Specifically, the conventional external power supply device operates in the charging mode to charge an internal battery of the power supply when connected to an adapter. The conventional external power supply operates in the discharge mode to apply power from the charged internal battery to a portable electronic device when the conventional external power supply device is connected to the portable electronic device and is not connected to an adapter.
In such a conventional external power supply device, power for the charging or discharging mode is supplied through one terminal. A toggle switch is provided, and the charging or discharging mode is selected according to the setting of the toggle switch. In this case, however, it is inconvenient for a user, as the user has to switch the toggle switch every time to change the charging/discharging mode; moreover, there may arise a problem that an incorrect switch setting will cause the internal battery to be discharged even though the adapter is connected to an external power source.
As described above, since the conventional external power supply device can operate only in either the charging mode or the discharging mode, power cannot be applied to the portable electronic device while the power supply charges the built-in battery. For this reason, it is impossible to connect a plurality of external power supply devices to the portable electronic device, as any external power supply device in the series that was charging would not supply power to the next power supply device in the series or to the portable electronic device.